1. Field of the Invention
This invention relates generally to the field of dishwashers and specifically to a dishwasher having a pump impeller provided with balancing vanes.
2. Description of the Related Art
Dishwashers, particularly those used in domestic applications, have a wash chamber conventionally provided with a sump at a lower part of the wash chamber. Wash liquid sprayed on dishes and other objects in the wash chamber flows downwardly into the sump where the liquid collects. The liquid can flow through a filter so that food particles are retained in a collection chamber of the sump. Filtered wash liquid in the sump is recycled to be sprayed on the dishes or directed toward a drain. The food particles are eventually pumped to the drain with the wash liquid. Such dishwashers are shown, for example, in U.S. Pat. Nos. 4,038,103 to Grunewald, 4,319,599 to Dingler, 4,347,861 to Clearman, 4,754,772 to Nord, 4,969,479 and 4,998,548 both to Lagerstrand. Large food particles may remain in the collection chamber causing unwanted clogging or odors.
In some installations, separate pumps (a recycling pump and a drain pump) are used to direct the liquid to the appropriate locations. In other installations, a single pump may be used in conjunction with a valve system to direct the liquid to either the drain or the wash chamber. An example of this is shown in U.S. Pat. No. 4,848,382 to Bertsch, incorporated herein by reference. Various applications have used impellers having vanes on both sides, as shown in U.S. Pat. Nos. 1,342,592 to Orr, 4,664,592 to Grzina, and 5,076,757 to Dorsch. Separate impellers on one shaft are shown in U.S. Pat. Nos. 4,799,855 to Milocco and 5,131,420 to Favret.
It would be preferable to use a single uni-directional motor to reduce cost and complexity, and improve efficiency. Advantageously, a shaft of the motor can extend through a wall separating the collection chamber from the pump chamber. Food particles and material from the dishes should not be recycled and should not interfere with the flow of liquid to the dishes or to the drain. In addition, it is desirable to isolate the pump from the food and other material to prevent clogging or damage to the pump.